Reaming apparatus

ABSTRACT

Tubing reaming apparatus comprises a housing adapted to be mounted to tubing to be reamed. The housing provides mounting for a reamer shaft adapted to mount a cutter within the tubing. The housing also provides mounting for a drive arrangement. A gear arrangement is provided between the drive arrangement and the reamer shaft. The housing may comprise a clamping arrangement adapted to reduce residual bend and ovality of the tubing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on, and claims priority from, GreatBritain Application Serial Number 0424885.2, filed Nov. 11, 2004, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

This invention relates to reaming apparatus. In particular, but notexclusively, the invention relates to reaming apparatus for use inreaming tubing such as coiled tubing. Aspects of the invention alsorelate to methods of forming and machining tubing, particularly methodssuitable for on-site use.

BACKGROUND OF THE INVENTION

In the oil and gas industry, devices are often run into wells on lengthsof flexible metallic hollow tubing which may stored coiled on a spool;the tubing is thus known as coiled tubing. Individual lengths of coiledtubing, which may be hundred of metres long, are joined by means ofappropriate in-line connectors that fit and seal within the ends of thelengths. Coiled tubing is normally formed from strip rolled into acylindrical form and then welded. As noted above, the tubing is thencoiled for storage and transport. Thus the tubing forming operation, andsubsequent handling and coiling of the tubing, normally results in thetubing featuring a degree of ovality and residual bend. Furthermore, theinternal diameter of tubing formed from strip includes an axial weldseam. Accordingly, to prepare the end of a tubing length to receive aconnector, particularly a connector featuring an elastomer seal, it isnormal practice to ream the tubing end using a tool such as theapplicant's Internal Combination Reamer System (ICRS) unit. This is ahand operated, self-aligning unit that prepares coiled tubing to acceptthe applicant's Elastomer Sealed Inline Connector. The ICRS toolfeatures a two-part sleeve, one part of the sleeve for location over theend of the tubing and being fixed to the tubing using grub screws, andthe other part of the sleeve providing mounting for a shaft extendinginto the sleeve. A reamer or other cutter is mounted on the end of theshaft within the sleeve, while a handle for rotating the reamer isprovided on the other end of the shaft. An Acme thread couples the partsof the sleeve, such that relative rotation of the parts advances thereamer into the tubing on which the sleeve is mounted. Thus, using thehandle to rotate the shaft and turn the reamer while rotating the sleeveparts to feed the reamer through the tubing, a skilled operator may usethe ICRS tool to ream the end of a tubing length to produce anacceptable seal bore finish on the tubing internal diameter, ready toreceive a connector. However, this is a time-consuming operation. Forexample, reaming a 2⅞″ (7.3 cm) outside diameter 0.190″ (0.48 cm) wallthickness coiled tubing to a depth of 7″ (17.8 cm) will typically takearound four hours. Furthermore, inexperienced or unskilled operatorsoften have difficulty in achieving the level of finish necessary toachieve a fluid-tight seal between the tubing and a connector, andfurthermore will often damage the reamer: one common problem is that thereamer is advanced too quickly into the tubing and when the reamer isrotated the reamer takes too big a “bite” of the tubing wall, whichleads to a poor finish and damage to the reamer. It is also difficult toream the larger sizes of coiled tubing, due to the torque required toturn the cutter.

It is among the objectives of embodiments of the invention to provide areaming apparatus that obviates or mitigates at least some of thesedifficulties.

SUMMARY OF THE INVENTION

In general, the preferred embodiments of the invention relate toapparatus and methods for use in machining operations in which amachining apparatus is mounted to and supported by a work piece. Forexample, the work piece may be a large spool of coiled tubing and it isof course impractical to mount such a spool on a machine tool. Also,embodiments of the invention relate to apparatus which is portable andcan be moved or carried, often by one person, to an appropriate locationin a work site. Thus, the apparatus may be brought to a large workpiece, rather than having to move the work piece. Embodiments of theinvention are also suitable for manual operation by a single operator.

In accordance with a first aspect of the present invention there isprovided apparatus for reaming tubing, the apparatus comprising:

-   -   a housing providing mounting for a cutter; and    -   a clamping arrangement adapted to locate the housing relative to        tubing to be reamed, the clamping arrangement being adapted to        reduce at least one of residual bend and ovality of the tubing.

The invention also relates to a method of reducing at least one ofresidual bend and ovality in tubing prior to a machining operation, themethod comprising locating a clamping arrangement on tubing to bemachined, and actuating the clamping arrangement to deform the tubing toa desired tubing form.

The method may further comprise the step of mounting tubing machiningapparatus relative to the tubing via the clamping arrangement.

The reaming operation may be carried out such that the tubing mayreceive a tool or device, such as an in-line connector. By reducing oreliminating residual bend or ovality the clamping arrangementfacilitates the subsequent reaming operation by straightening the tubingand improving the circularity of the tubing. Using a conventionalclamping arrangement utilising grub screws will have little or no effecton the residual bend or ovality of the tubing, and in some cases mayactually create ovality: reaming bent or oval tubing results in anuneven cutting process, as the depth of material cut from the tubingwall will vary around the circumference of the tubing. This will in turnresult in the reamed wall of the tubing having a varying thickness andin some cases this may result in an unacceptable weakening of thetubing.

The clamping arrangement may comprise two or more parts defining contactsurfaces for collectively defining a cylindrical form corresponding to adesired tubing form. The defined cylindrical form may be substantiallycontinuous or may be discontinuous, for example the form may be definedby a plurality of point or line contacts. In a preferred form theclamping arrangement comprises two parts each defining asemi-cylindrical form. The parts may be configured in a loadingconfiguration, to permit the parts to be positioned around the tubing,and in a clamping configuration, in which the contact surfaces engagethe tubing surface. The clamping arrangement may further compriseretainers operable to retain the parts in the clamping configuration.Preferably the retainers are operable to apply force to the partssufficient to deform the tubing such that the tubing is at leastpartially straightened or the ovality of the tubing is reduced. In apreferred embodiment the retainers comprise threaded members, such asscrews, extending between the parts and which may be rotated andtightened to bring the parts together. However, other retainerconfigurations may also be used, including cam or clamp arrangements.The preferred retainers are manually operable, but in other embodimentsthe retainer may be powered, for example hydraulically or electricallyactuated.

Preferably, the cylindrical form defined by the parts has an axialextent greater than the diameter of the form. Most preferably, thecylindrical form has an axial extent two or more times the formdiameter.

The clamping arrangement may be integral with the housing, but mostpreferably is separable from the housing and includes at least onehousing engaging member or profile.

Another aspect of the invention relates to a clamping arrangementadapted to reduce at least one of residual bend and ovality of a tubingfor other purposes, for example to facilitate location of a tool ordevice on the exterior of the tubing.

According to another aspect of the present invention there is providedapparatus for reaming tubing, the apparatus comprising:

-   -   a housing adapted to be mounted to tubing to be reamed, the        housing providing mounting for (a) a reamer shaft, the shaft        adapted for mounting a cutter within tubing to be reamed,        and (b) a drive arrangement; and    -   a gear arrangement between the drive arrangement and the reamer        shaft.

The invention also relates to a method of reaming tubing, the methodcomprising:

-   -   mounting a housing to tubing to be reamed such that a cutter        mounted on a reamer shaft mounted to the housing is located at        least partially within the tubing; and    -   driving the reamer shaft to rotate the cutter via a gear        arrangement.

The provision of a gear arrangement allows the nature of the input tothe drive arrangement to be modified on transfer to the reamer shaft,preferably by reducing drive speed and increasing drive torque. Thisfacilitates manual operation of the apparatus, by increasing the torqueapplied to the reamer shaft and thus facilitating the cutting of thetubing. Furthermore, this arrangement also facilitates adaptation of theapparatus for powered operation, for example by coupling the bit of anelectric drill to the drive arrangement.

The drive arrangement may take any appropriate form, but preferablyincludes an operator handle adapted for rotation by an operator. In oneembodiment the drive arrangement includes a crank handle. Compared toconventional reaming apparatus, the apparatus of embodiments of thisaspect of the present invention may accommodate relatively high speedlow torque inputs, which it is generally easier to apply manually. Forexample, one embodiment of the apparatus may be comfortably operated ata drive speed of 4 rpm by application of a relatively light load,compared to a typically drive speed of around 1 rpm, requiringapplication of significant force, for a conventional reaming apparatus.It is of course generally easier to apply a lighter load consistently,as a manually applied higher load will tend to be appliedintermittently. Thus, this aspect of the invention will tend to lead toa more consistent and better quality finish on the work piece, and lessload and wear to the cutter.

Preferably, the drive arrangement includes a drive shaft. Mostpreferably, the drive shaft is coaxial with the reamer shaft.

Preferably, the gear arrangement includes a spur gear arrangement, inwhich a gear wheel mounted to a drive shaft engages at least one pinion.The pinion may be a double gear and mate with a gear wheel coupled to ormounted on the reamer shaft. Of course other embodiments may featuredifferent gear configurations and arrangements.

This aspect of the invention may further comprise a cutter advancearrangement adapted to advance the reamer shaft axially of the housingwith rotation of the reamer shaft.

According to a further aspect of the present invention there is providedapparatus for reaming tubing, the apparatus comprising:

-   -   a housing adapted to be mounted to tubing to be reamed, the        housing providing mounting for a reamer shaft adapted for        mounting a cutter within tubing to be reamed; and    -   a cutter advance arrangement adapted to advance the reamer shaft        axially of the housing with rotation of the reamer shaft.

The invention also relates to a method of reaming tubing, the methodcomprising:

-   -   mounting a housing to tubing to be reamed, the housing providing        mounting for a reamer shaft and a cutter;    -   driving the reamer shaft to rotate the cutter; and    -   advancing the cutter axially of the tubing at a rate related to        the rotation of the cutter.

These aspects of the invention provide for automatic feed of the cutterwith rotation of the cutter. This avoids the difficulties associatedwith conventional reaming apparatus in which advancement of the cutteris manually controlled independently of cutter rotation, with the resultthat cutter feed is likely to be intermittent and often at aninappropriate rate.

Preferably, the cutter advance arrangement is geared to the reamer shaftto provide an appropriate rate of advance. In other embodiments thecutter advance rate may be related to other parameters, for examplecutter loading.

Preferably, the cutter advance arrangement includes a threaded portionfor engaging a corresponding threaded portion on the housing. In oneembodiment the cutter advance arrangement includes an external threadand the housing defines an internal thread.

Preferably, the housing also provides mounting for a drive arrangementand a gear arrangement between the drive arrangement and the reamershaft. Alternatively, or in addition, the housing may include a geararrangement between a drive arrangement and the cutter advancearrangement, which gear arrangement may include a pinion engaging a ringgear on a threaded portion of the cutter advance arrangement. In apreferred embodiment, a common or linked gear arrangement is providedbetween the drive arrangement and both the reamer shaft and the cutteradvance arrangement. Preferably, the gear arrangement between the drivearrangement and the cutter advance arrangement is adapted to beselectively inactivated, isolated or otherwise modified to permit morerapid drive of the cutter advance arrangement. This is useful when it isdesired to retract the cutter, or when there is little load on thecutter advance arrangement, and there is no requirement to provide arelatively low speed or high torque input to the cutter advancearrangement. The gear arrangement may include a gear mounting providingmounting for a pinion, which gear mounting may be selectively configuredto be locked against rotation relative to the housing such that rotationof the pinion results in rotation of a ring gear engaging the pinionrelative to the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described,by way of example, with reference to the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a clamping arrangement in accordancewith an embodiment of an aspect of the present invention;

FIG. 2 is a sectional view of a reaming apparatus in accordance with anembodiment of a further aspect of the present invention; and

FIGS. 3, 4, 5 and 6 are sectional views on lines 3-3, 4-4, 5-5 and 6-6of the reaming apparatus of FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a clamp 10 to be used in conjunction with a reamingapparatus 12 as illustrated in section in FIG. 2 of the drawings. Aswill be described, the clamp 10 is adapted to be mounted to the end of alength of tubing, in this example 2.875″ (7.3 cm) outside diametercoiled tubing, and the reamer 12 is fixed to the clamp 10 to permit areaming operation to be carried out on the tubing.

The clamp 10 comprises two parts 14, 15 releasably secured together byeight cap head screws 16. The clamp parts 14, 15 collectively define acylindrical inner surface defining an inside diameter of 2.875″ (7.3cm). Thus, with the screws 16 loosened, the clamp parts 14, 15 may befitted over the end of a length of 2.875″ (7.3 cm) o.d. coiled tubing.Tightening the screws 16 brings the inner surfaces of the parts 14, 15into contact with the tubing and, if the tubing features any ovality orresidual bend, continue tightening of the screws 16 will deform thetubing and force the tubing wall to conform to the internal diameter ofthe parts 14, 15, thus straightening the tubing and removing anyovality. Furthermore, the tight engagement of the parts 14, 15 with thetubing also provides a secure mounting for the reamer 12 on the tubing,as will be described.

From FIG. 1 it will be noted that the clamp 10 features operator handles18 to assist an operator in manipulating the clamp 10. Furthermore, theend of the clamp 10 to be positioned at the free end of the tubingdefines a socket 20 adapted to receive the reduced diameter leading endof a sleeve 22 forming the outer body of the reamer 12. Additionally,the clamp 10 features two reamer retaining screws 24 for engaging withcorresponding sockets 26 formed in the end of the sleeve 22.

As noted above, in use the reamer 12 is mounted to the end of a lengthof coiled tubing, via the clamp 10. When the reamer 12 is mountedrelative to tubing in this manner, a cutter 30 located on the free endof a reamer shaft 32 which extends from the sleeve 22 is locatedadjacent the end of the tubing. An operator handle 34 featuring a crank36 is provided at the opposite end of the reamer 12. Rotation of thehandle 34 by an operator turns a drive shaft 38. Rotation of the driveshaft 38 is transferred to the reamer shaft 32 via a reduction gearbox40 located within the sleeve 22. Furthermore, the gearbox 40 carries anexternally threaded ring 42 linked to the drive shaft 38 via the gearbox40. The threaded ring 42 engages with a corresponding thread 44 providedon the inner surface of the sleeve 22 such that the rotation of thedrive shaft 38 also causes the gearbox 40 to advance axially through thesleeve 22, and thus the cutter 30 to advance axially through the tubingbeing reamed.

During a reaming operation, rotation of the gearbox 40 relative to thesleeve 22 is prevented by engagement of a radially extending key 46mounted in a front gearbox housing 48 with a closed end slot 50extending axially along the lower edge of the sleeve 22. However, whenthe key 46 is retracted from the slot 50, as illustrated in FIG. 2, thegearbox 40 and threaded ring 42 may be rotated directly which, as willbe described, facilitates retraction of the cutter 30.

The construction and operation of the reamer 12 will now be described ingreater detail, with reference also being made to FIGS. 3 to 6 of thedrawings, which illustrate sectional views of the gearbox 40, and towhich reference will be made to described the operation of the reamergear train.

As noted above, the reamer 12 features an operator handle 34. The handle34 comprises two radial rods 52, 53 the inner ends of which are threadedand engage corresponding threaded sockets in the free end of the driveshaft 38, the rods 52, 53 being locked in place by respective roll pins54. Ball knobs 56 are provided on the free ends of the rods 52, 53, andthe crank handle 36 is mounted towards the outer end of one of the rods52.

Although the reamer 12 is primarily intended for manual operation, insome circumstances it may be desired to operate the reamer 12 using apower drive, and for this purpose the end of the drive shaft 38 includesa hexagonal recess 58.

From the handle 34, the drive shaft 38 extends into a smaller diametersleeve 62 forming part of a rear gearbox housing 60. The shaft 38 ismounted relative to the sleeve 62 by a bush 64. The rear gearbox housing60 is secured to the front gearbox housing 48 by means of three cap headscrews 66 which, as will be described, also provide mounting for pinionswithin the gearbox 40.

The inner end of the drive shaft 38 is retained within the housing 60 bya retainer ring 68 engaging a shoulder in the housing 60 via a bush 70.The retainer ring 68 is itself secured to the drive shaft 38 by a shortinput shaft 72 which extends into a blind bore 74 in the end of theshaft 38, and is retained therein by grub screws 76.

Reference is now also made to FIG. 3, which shows the sixteen toothedend of the input shaft 72 engaging with three thirty two toothed doublepinion gears 78 a. The pinion gears 78 are mounted within the housing 60on the shafts of the screws 66. With the drive shaft 38 and input shaft72 revolving at 4 rpm clockwise, the double pinion gear 78 will revolveat 2 rpm anticlockwise.

Reference is now made to FIG. 4 of the drawings, which section shows thesmaller sixteen tooth part of the double pinion gears 78 b mating with athirty two tooth output shaft 80 a. With the double gear 78 rotating at2 rpm anticlockwise, the output shaft 80 rotates at 1 rpm clockwise.

If reference is made to FIG. 2, it will be noted that the output shaft80 is coaxial with and coupled to the reamer shaft 32 via a shaftretainer 82 and key 84. The reamer shaft 32 is located relative to thefront gear housing 48 by two bushes 86, 87 and also passes through anannular swarf trap 88 towards the front of the sleeve 22.

Reference is now made to FIGS. 5 and 6 of the drawings, which illustrateelements of the gearbox 40 which provide drive to the threaded ring 42that provides for feed of the cutter 30 into the tubing to be cut. FIG.5 shows a sixteen tooth gear 80 b on the output shaft 80 which mateswith a thirty two tooth double gear 92 a mounted on the shaft of one ofthe screws 66. With the output shaft 80 revolving at 1 rpm clockwise,the double gear 92 revolves at 0.5 rpm anticlockwise.

Reference is now made to FIG. 6 which shows the sixteen tooth doublegear 92 b mating with a sixty six toothed ring gear 94 provided on theinner diameter of the threaded ring 42. With a double gear 92 revolvingat 0.5 rpm anticlockwise, the ring gear 94 revolves at 0.121 rpmanticlockwise. This translates to a feed of 0.015″ (0.04 cm) per cutterrevolution using an eight tpi thread on the ring 42.

As noted above, the gear housing 48, 60 is normally held againstrotation relative to the sleeve 22 by the key 46 which is urged toextend into the slot 50 by a spring 96. However, if desired, the key 46may be retracted, out of engagement with the slot 50, by pushing the endof a key rod 98 into a recess 100 in the key 46. The key rod 98 extendsthrough the gear housing 48, 60 from a feed ring 102 mounted on the reargearbox housing 60, which ring 102 is pressed forward to retract the key46 and may be pulled rearwardly by an operator to release the key 46.FIG. 2 shows the key 46 in the retracted configuration. An operatorwould retract the key 46 after completion of a reaming operation toallow more rapid translation of the gearbox 40 to the rear end of thesleeve 22. In particular, with the key 46 retracted, the drive shaft 38is prevented from rotating by holding the handle 34. The gearbox 40 isthen turned clockwise by the operator gripping the sleeve portion 62 totranslate the gearbox 40, and thus also the cutter 30, back along theleft hand Acme sleeve thread 44.

In use, the clamp 10 and reamer 12 will typically be used to prepare theend of a length of coiled tubing ready to receive an in-line connector.This involves provision of a relatively smoothed-walled recess in theend of the tubing such that the inline connector may be received andsealed within the end of the tubing.

If possible, the end of the tubing will be first located at a suitableheight for working, and the tubing end supported and secured. The clamp10 is then located over the end of the tubing, with the free end of thetubing located adjacent the base of the clamp socket 20. The clampscrews 16 are then tightened. As the semi-cylindrical clamp parts 14, 15are brought together the clamp part surfaces will straighten anyresidual bend in the tubing and will also reduce or remove ovality inthe tubing end.

Once the clamp 10 has been secured to the tubing, the reamer 12 may bemounted to the clamp, and secured in place by extending the screws 24into the reamer sleeve sockets 26. At the start of a reaming operation,the gearbox 40 will be located at the rear end of the sleeve 22 toposition the cutter 30 adjacent the end of the clamped tubing. Thecutter 30 is located on the end of the reamer shaft 32 by a collar 104,which may be removed to allow replacement of the cutter 30 as required.

The operator then utilises the handle 18 to rotate the drive shaft 38.As noted above, rotation of the handle 18 and shaft 38 at 4 rpm istranslated to rotation of the reamer shaft 32 at 1 rpm, with acorresponding increase in torque applied to the reamer shaft 32. Therotating cutter 30 provides a full diameter cut. Furthermore, with eachrotation of the cutter 30 the rotation of the threaded ring 42 producesa feed of 0.015″ (0.04 cm) of the gearbox 40 relative to the sleeve 22,and thus of the cutter 30 relative to the tubing.

The cutter 30 will thus be rotated and simultaneously fed through thetubing, removing the weld bead from the tubing and providing a reamedrecess with a cylindrical surface with the finish necessary to form aseal bore and accept an elastomer sealed inline connector.

Once the tubing has been reamed to the appropriate depth, or if thereaming operation encounters a problem, or the gearbox 40 has reachedthe end of its travel within the sleeve 22, the operator retracts theanti-rotation key 46 from the sleeve slot 50 by pressing the feed ring102. The operator then holds the handle 18 stationary while turning thesleeve 62 to retract the cutter 30 from the tubing and move the gearbox40 back towards the rear of the sleeve 22. Accordingly, the reamer 12may be returned to its initial configuration relatively quickly, readyfor the next reaming operation.

The reamer 12 may then be dismounted from the clamp 10. A connector isinserted into the reamed coiled tubing before the clamp 10 is dismountedfrom the tubing, as otherwise the coiled tubing may spring back to abent or oval form, preventing insertion of the connector.

It will be apparent to those of skill in the art that the abovedescribed clamp 10 and reamer 12 provide for effective and relativelystraightforward reaming of coiled tubing to provide a seal bore, and theset-up and operation of the clamp 10 and reamer 12 is such that theoperation may be completed to a high standard by relatively unskilledpersonnel. The provision of a reamed socket in the tubing may also beachieved relatively quickly: in testing, a length of 2⅞″ (7.3 cm)outside diameter 0.190″ (0.48 cm) wall coiled tubing was reamed to adepth of 7″ (17.8 cm) in approximately 1.5 hours using the clamp 10 andreamer 12 as described above. This compares favourably to the 4 hoursrequired to complete this task by a skilled operator utilising aconventional reaming tool.

Although reference has been made primarily herein to reaming of coiledtubing, those of skill in the art will recognise that aspects of thepresent invention may be used in a wide variety of applications forexecuting cutting, machining and other operations, including laser orwater jet cutting, testing, inspection and surveying on work pieces of avariety of forms. Furthermore, the cutter used in the various aspects ofthe invention may take any appropriate form. Conventionally, coiledtubing reaming is undertaken using a fixed diameter fluted cutter, andan operator will utilise a cutter intended to ream a coiled tubing ofpredetermined diameter and predetermined wall thickness. However, theinvention may also utilise a cutter head with a single tool bit, whichbit may be adjustable to provide a variety of cutting diameters andcutting depths. This provides the apparatus with greater flexibility,but does require a degree of operator skill to correctly adjust and setthe bit.

1. Apparatus for reaming tubing, the apparatus comprising: a housingadapted to be mounted to tubing to be reamed, the housing providingmounting for (a) a reamer shaft, the shaft adapted to mount a cutterwithin tubing to be reamed, and (b) a drive arrangement; a geararrangement between the drive arrangement and the reamer shaft, the geararrangement being adapted to modify the nature of an input to the drivearrangement on transfer to the reamer shaft; and a cutter advancearrangement adapted to advance the reamer shaft axially relative to thehousing.
 2. The apparatus of claim 1, wherein the gear arrangement isadapted to reduce drive speed and increase drive torque.
 3. Theapparatus of claim 1, wherein the drive arrangement is adapted to bemanually driven.
 4. The apparatus of claim 1, wherein the drivearrangement is adapted to be powered.
 5. The apparatus of claim 4,wherein the drive arrangement is adapted to engage a power inputcoupling.
 6. The apparatus of claim 1, wherein the drive arrangementincludes an operator handle adapted for rotation by an operator.
 7. Theapparatus of claim 6, wherein the operator handle includes a crankhandle.
 8. The apparatus of claim 1, wherein the drive arrangementincludes a drive shaft.
 9. The apparatus of claim 8, wherein the driveshaft is coaxial with the reamer shaft.
 10. The apparatus of claim 1,wherein the gear arrangement includes a spur gear arrangement, in whicha gear wheel mounted to a drive shaft mates with at least one pinion.11. The apparatus of claim 10, wherein the pinion is a double gear andmates with a gear wheel coupled to the reamer shaft.
 12. The apparatusof claim 1, wherein the cutter advance arrangement is adapted to advancethe reamer shaft axially of the housing with rotation of the reamershaft.
 13. The apparatus of claim 12, wherein the cutter advancearrangement includes a threaded portion for engaging a correspondingthreaded portion on the housing.
 14. The apparatus of claim 13, whereinthe cutter advance arrangement includes an external thread and thehousing defines an internal thread.
 15. The apparatus of claim 12,wherein the gear arrangement includes a pinion engaging a ring gear on athreaded portion of the cutter advance arrangement.
 16. The apparatus ofclaim 12, wherein a linked gear arrangement is provided between thedrive arrangement and both the reamer shaft and the cutter advancearrangement.
 17. The apparatus of claim 12, wherein the gear arrangementincludes a gear mounting providing mounting for a pinion, which gearmounting may be selectively configured to be locked against rotationrelative to the housing such that rotation of the pinion results inrotation of a ring gear mating with the pinion relative to the housing.18. The apparatus of claim 1, further comprising: a clamping arrangementadapted to locate the housing relative to the tubing to be reamed, theclamping arrangement being adapted to reduce at least one of residualbend and ovality of the tubing.
 19. The apparatus of claim 18, whereinthe clamping arrangement is adapted to reduce both residual bend andovality of the tubing.
 20. The apparatus of claim 18, wherein theclamping arrangement comprises at least two parts defining contactsurfaces for collectively defining a cylindrical form corresponding to adesired tubing form.
 21. The apparatus of claim 20, wherein thecylindrical form is substantially continuous.
 22. The apparatus of claim20, wherein the clamping arrangement comprises two parts each defining asemi-cylindrical form.
 23. The apparatus of claim 20, wherein the partsare adapted to be configured in a loading configuration and in aclamping configuration.
 24. The apparatus of claim 23, wherein theclamping arrangement further comprises retainers operable to retain theparts in the clamping configuration.
 25. The apparatus of claim 24,wherein the retainers are operable to apply force to the parts to deformthe tubing.
 26. The apparatus of claim 25, wherein the retainerscomprise threaded members extending between the parts.
 27. The apparatusof claim 20, wherein the cylindrical form defined by the parts has anaxial extent greater than the diameter of the form.
 28. The apparatus ofclaim 27, wherein the cylindrical form has an axial extent at least twotimes the diameter of the form.
 29. The apparatus of claim 18, whereinthe clamping arrangement is separable from the housing.
 30. Theapparatus of claim 18, wherein the clamping arrangement includes atleast one housing engaging member.
 31. A method of reaming tubing, themethod comprising: mounting a housing to tubing to be reamed, a cutterbeing mounted on a reamer shaft mounted to the housing; engaging thetubing with the cutter; applying an input force to drive the reamershaft and rotate the cutter via gearing which modifies the nature of theinput force on transfer to the reamer; and advancing the cutter withrotation of the reamer shaft.
 32. The method of claim 31, comprisingapplying an input torque at an input speed to the gearing and therebyapplying an increased torque at a reduced speed to the reamer shaft. 33.The method of claim 31, comprising applying a manually applied inputtorque to the gearing.
 34. The method of claim 31, comprising applying apowered input to the gearing.
 35. The method of claim 31, comprisingvarying the relationship between the rate of advance of the cutter andthe rate of rotation of the cutter.
 36. The method of claim 31, furthercomprising locating a clamping arrangement on the tubing, the clampingarrangement defining a desired tubing form, and actuating the clampingarrangement to deform the tubing to said desired tubing form.
 37. Themethod of claim 36, comprising reducing at least one of residual bendand ovality of the tubing.
 38. The method of claim 37, comprisingreducing both residual bend and ovality of the tubing.
 39. The method ofclaim 36, further comprising mounting the housing relative to the tubingvia the clamping arrangement.
 40. The method of claim 36, comprisingclamping the tubing between at least two parts defining contact surfacescollectively defining a cylindrical form.
 41. The method of claim 31,wherein the tubing is coiled tubing.